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Finding the Fourth Proportional to 859.82, 1,185.66 and 639.20

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Solution

The fourth proportional to 859.82, 1,185.66 and 639.20 is: 881.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    859.82 : 1,185.66 = 639.20 : x
  2. Step 2: Convert to fraction form
    859.82/1,185.66 = 639.20/x
  3. Step 3: Cross multiply
    859.82x = 1,185.66 × 639.20
  4. Step 4: Simplify right side
    859.82x = 757,873.87
  5. Step 5: Solve for x
    x = 757,873.87/859.82
  6. Step 6: Final answer
    x = 881.43

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.